It is well known to connect the ends of sheet metal ducts by providing the ducts at opposite ends of the panels of the ducts which open towards one another and wherein there is disposed at the corners of the ducts angle plates which have opposite ends thereof seated in and connect together adjacent angle flanges. The ducts are then secured together by way of fasteners which connect together the angle plates.
Attention is here directed to the patents to Heilman et al, U.S. Pat. No. 4,466,641, and La Crosse et al, U.S. Pat. No. 4,542,923, which clearly disclose ducts formed with the channel flanges into which there are forced angle plates by way of which the ducts are connected together by bolts passing through the angle plates.
To date, the angle plates are manually secured to the ducts by manually forcing the angle plates into the duct channel flanges. This is time consuming and thus costly. Further, each angle plate must be positioned individually.